identification of hydrocarbon degrading bacteria genus from oil-crude contaminated soils

background: long-term extraction and production of various oil derivatives causes contamination of soil adjacent to production and refining area. the main important issue is the ecological hazard of these pollutants. the main aim of the study was to identify and separate native bacteria that are responsible for degradation of oil contaminated fields. methods: we prepared a compound sample of contaminated soil in the vicinity of oil wells drilled in marun oil field of ahwaz, iran. moreover, an uncontaminated sample was picked from the same area and deliberately contaminated with crude oil in a 5 wt% rate. the number of oil degrading bacteria was counted by mpn (most probable number ) method. then, the bacteria was cultured and isolated in a rich agar medium and late discrimination test was done by gram staining and biochemical tests at the level of family or genus. findings: the number of bacteria in naturally contaminated and artificially soil was 6.8 × 10 5 and 3.5 × 10 7 , respectively. the majority of bacteria responsible for oil degradation were s taphylococcus, acinetobacter and flavobacterium genus in naturally contaminated soil; however, a cinetobacter, pseudomonas and moraxella genus were the main bacteria in artificially-contaminated soil samples. conclusion: it is recommended to be used for bioremediation of native organisms and bio-power and robust.